Tuesday's indictment charges Robert Butyka, 25, with one count of unauthorized impairment of a protected computer, according to the U.S. attorney's office in Los Angeles.

Officials said the 2010 attack made computers in the Atmospheric Infrared Sounder Program unusable for two months while malicious code was removed and data restored. The program is used in climate research and weather forecasting.

The U.S. attorney's office said NASA worked with Romanian authorities, resulting in Butyka's conviction in Romania last month. He has been sentenced to three years in prison there and would face a sentence of up to 10 years if convicted in the U.S.

JPL spokeswoman Veronica McGregor said it won't disclose how far the hacker got into the system, but he wasn't able to access the Atmospheric Infrared Sounder instrument in space that transmits weather measurements back to Earth.

Damage from the hacking was estimated at $500,000, including costs of work on the computers and lost research time.